A method for starting a continuous casting

ABSTRACT

A heat sink casting is cast around the exposed portion of a conventional starting bolt, stud or pin to prevent the starting bolt, stud or pin from being softened and failing when the cast or strand is started. The heat sink casting may be cheaply made concurrently with the drawing of the spectrograph sample which is taken of each heat.

United States Patent [72] lnventor Thomas H. Brennan Upland, Calif.

[21] Appl. No. 65,273

[22] Filed Aug. 19, 1970 [45] Patented Nov. 30, 1971 [73] Assignee American Pipe and Construction Co. Los Angeles, Calif.

Original application Feb. 15, 1968, Ser. No. 705,762, now abandoned. Divided and this application Aug. 19, 1970, Ser. No. 65,273

[54] METHOD FOR STARTING A CONTINUOUS CASTING 1 Claim, 11 Drawing Figs. [52] US. Cl 164/82, 164/274 [51] Int. Cl B2211 11/08 [50] Field of Search 164/82,

[56] References Cited UNITED STATES PATENTS 2,070,892 2/1937 Gamble 164/111 X 2,266,432 12/1941 Morin et al. 164/111 X 3,050,792 8/1962 Lipman et al. 164/282 X 3,333,627 8/1967 Forster 164/282 FOREIGN PATENTS 725,323 3/1955 Great Britain 164/274 SB Primary Examiner-R. Spencer Annear Attorney-Mellin, Moore & Weissenberger ABSTRACT: A heat sink casting is cast around the exposed portion of a conventional starting bolt, stud or pin to prevent the starting bolt, stud or pin from being softened and failing when the cast or strand is started. The heat sink casting may be cheaply made concurrently with the drawing of the spectrograph sample which is taken of each heat.

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THOMAS H. BRENNAN BY /wea L M I- v, ATTORNEYS 1 A METHOD FOR STARTING A CONTINUOUS CASTING CROSS-REFERENCE TO RELATED APPLICATION This application is a division of Ser. No. 705,762, filed Feb. 15, 1968, now abandoned.

BACKGROUND OF THE INVENTION In the continuous casting art, it is customary to provide a starting bar which is inserted into the lower end of the mold and is then drawn out to start the continuous casting process. The starting bar is customarily attached to the continuous cast or strand by means of a starting bolt or pin which is fastened to the starting bar. To start the strand, molten metal is cast around the exposed portion of the starting bolt where it solidifies rapidly and interlocks with an appropriate interlocking surface, e.g., an enlarged head, of the starting bolt or pin. As soon as this happens, the strand is anchored to the starting bar and the starting bar can be drawn out of the mold to start the continuous cast.

In the practice of the above-described process it soon became apparent that the heat of the molten metal which forms the strand was sufficiently great to soften the exposed end of the starting bolt or pin before the tip of the strand had hardened sufficiently for the starting bar to be drawn out of the mold. As a result, the exposed end of the starting bolt or pin would frequently fail by either distorting, parting or shearing off when the starting bar was moved, and the strand was consequently lost. It was therefore proposed to either provide several starting bolts or pins, or to use a fabricated shielded assembly, or to use a very large sized starting bolt. All of these methods, however, were cumbersome and presented handling problems. In addition, the use of an oversized or specially shaped starting bolt or pin caused a tremendous increase in unit cost over standard sized anchor members, such as bolts or headless studs and/or pins. Inasmuch as the anchor member is scrapped in the casting process, the use of oversized anchor members was found to be highly disadvantageous economically.

SUMMARY OF THE INVENTION The present invention overcomes the above-cited difficulties by providing the anchor member with a special heat sink casting which is precast around the head of the anchor member and engages the head of the anchor member in the same locking relationship in which the strand eventually engages the heat sink casting. In this way, tensional failure of the exposed end of the anchor member due to softening is avoided, and yet the anchor member can be of relatively small size.

The heat sink casting may conveniently be made concurrently with the drawing of the spectrographic sample which is normally drawn from each furnace heat, preparatory to the pouring of a strand, to perform the necessary spectrographic analysis ofthe heat.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I schematically shows the relationship of the starting bar, anchor member, mold and tundish in a typical continuous casting process;

FIGS. 2a through 2e are elevational views, with the heat sink in section, of various examples of possible embodiments ofthe invention;

FIG. 3 is a bottom view of FIG. 2a;

FIGS. 4 through 7 are views of various examples of possible configurations of the heat sink casting, with FIG. 7 being a bottom view of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the water-cooled mold of a continuous casting apparatus at 10. Prior to the commencement of a continuous cast, a starting bar is inserted into the bottom opening of the mold, which it fills substantially completely. The starting bar is made up of a series of links 12, with the topmost link being a screw-threaded connector 14. It will be understood that in lieu of a screw-threaded connector 14, a different type of connector such as, for example, the keyed-pin connector of US. Pat. No. 3,239,894 may be used. The top end of the connector 14 may be packed off with asbestos cord 16 to prevent any molten metal from reaching the connector 14 and damaging it. A thick steel washer 18 in the shape of the mold may be placed above the connector 14 to prevent adherence of the continuous cast strand to the top surface of connector 14. The starting bolt or other anchor member 20 is then attached to the connector 14 to hold the washer 18 in place and to provide an anchor for the strand. Pieces of reinforcing rod or other steel scrap 22 are customarily placed around the anchor member 20 to rapidly chill the bottom edge of the strand and to prevent it from adhering to the washer 18 or connector 14. The chilling provided by the rods 22 also assists the rapid solidification of the tip of the strand about the anchor surface 24 of the anchor member 20.

When the casting of the strand commences, a stream 26 of molten metal is permitted to pour out of the tundish 28 into the mold 10. Due to the water-cooling (not shown) of the mold l0 and due to the heat-absorbing capacity of the rods 22 and of the heat sink casting which constitutes the head of anchor member 20 in FIG. 1, the strand rapidly solidifies around the anchor member 20 as shown at 30, while the upper portion 32 of the cast fills the mold but remains liquid for a short while longer.

As soon as the strand has solidified around the anchor member as at 30, the starting bar can be pulled downwardly and the anchor member will draw the solidified tip portion 30 of the strand with it. As the solidified portion 30 is drawn out of the mold, the portions of the strand lying above it in the mold solidify under the influence of the water-jacket of the mold, and a continuous solidified strand of metal thereafter exits from the bottom part of the mold 10.

Referring now to FIGS. 2a e, it will be seen that the elongated member around which the heat sink is cast may consist of a standard bolt such as shown in FIG. 2a, or of a stud or rod, threaded or unthreaded, of any cross section, with or without a head, and with or without one or more pins. The anchor member may in fact have any configuration as long as it satisfies two requirements: First, it must have a lower portion arranged in some manner for attachment to the starting bar so that it can be pulled downwardly by the starting bar; and second, it must have an upper exposed portion so arranged that when a heat sink casting is cast around it, the heat sink casting cannot be pulled off the anchor member when the starting bar pulls the anchor member down.

The latter requirement may be satisfied in many ways, for example by a bent or deformed elongated member, or by any configuration of the elongated member which provides a portion of smaller cross section below a portion of larger cross section. For example, the head of a bolt (38 in FIG. 2a), screw threads on a stud (36 in FIG. 2b), a deformed end of a pin or stud (37 in FIG. 2c), a nut threaded on a stud (39 in FIG. 2d), a recess in the side of a pin, or a transverse hole (41 in FIG. 2e) with or without a pin (43 in FIG. 22) through it are all examples of configurations which satisfy this requirement. Obviously, there are many others.

The manufacture and functioning of the device of this invention are the same regardless of the specific configuration used. Taking FIG. 2a as an example, a heat sink casting 40 is cast around the upper portion of the shank of the elongated member 34, there shown as a bolt, prior to the attachment of the elongated member 34 to the connector member 14. The heat sink casting 40 is allowed to cool before the elongated member 34 is inserted into the connector 14, so that it will have considerable heat-absorbing capacity. When the starting bar is now drawn downwardly, the drawing force is carried by the relatively large heat sink casting 40. Weakness of the anchor member 20 and its parting from the heat sink casting 40 is prevented partly because of the heat-absorbing capacity of the heat sink casting 40 itself, and partly by the fact that heat transmission from the heat sink 40 to the anchor member is retarded by the usually slightly oxidized interface between the heat sink casting 40 and the anchor member 34.

FIGS. 4 through 7 illustrate various shapes which the heat sink casting 40 can be made to take. It will be understood that these shapes are merely exemplary. Any shape would be suitable as long as it has enough volume to absorb sufficient heat to prevent weakening at any shear plane; and as long as its shape is such that a portion of smaller cross section lies below a portion of larger cross section, so that an interlocking surface will be presented to the solidifying strand to anchor the strand to the anchor member. Likewise, it will be understood that the shape of the cross section of the casting can be practically anything; however, it would usually be preferable to have either a circular cross section, which makes unnecessary any precise orientation of the bolt, or a cross section similar to the shape of the mold, which would make the entire heat sink surface equidistant from the walls of the mold for even heat distribution.

lt will be understood that the present invention can be carried out in many ways of which the depicted embodiments are merely illustrative. Consequently, the invention is not to be deemed limited by the embodiments shown, but merely by the scope of the following claims:

I claim:

1. The method of starting a continuous casting, comprising the steps of: a. forming an anchor member by casting a heat sink casting around one end of an elongated member;

b. permitting said heat sink casting to cool;

c. attaching the anchor member thus formed to a starting bar so as to position said anchor member in a continuous casting mold with said one end being exposed;

d. casting molten metal about said heat sink casting in said mold; and

e. drawing said starting bar through said mold as soon as said molten metal has solidified about said heat sink casting.

* l i i i 

1. The method of starting a continuous casting, comprising the steps of: a. forming an anchor member by casting a heat sink casting around one end of an elongated member; b. permitting said heat sink casting to cool; c. attaching the anchor member thus formed to a starting bar so as to position said anchor member in a continuous casting mold with said one end being exposed; d. casting molten metal about said heat sink casting in said mold; and e. drawing said starting bar through said mold as soon as said molten metal has solidified about said heat sink casting. 